Here's what you can do to protect yourself.


Flu season in the Southern Hemisphere can be an indication of what's in store for the Northern Hemisphere, and the recent flu season in Australia, where winter just ended, was one of the worst the country has ever seen. 

Until this year, 2017 was Australia's worst flu season to date, with more than 229,000 laboratory confirmed cases of influenza reported by the end of October. This year has already exceeded that, with 272,146 laboratory confirmed cases reported by the end of the first week of September, according to the Australian Department of Health.

(Those numbers might seem low for the US, which saw an estimated 48.8 million cases of the flu in 2017 season, according to the Centers for Disease Control and Prevention. But keep in mind, the US population is more than 13 times that of Australia.) 

Australia's season also started and peaked early. Typically, flu season down under spans from June to October and peaks in August or September. This year, however, there was increased influenza activity March through May, and the season peaked in June and July.

So how worried do we really need to be? Vanessa Raabe, MD, assistant professor of pediatric infectious disease at NYU Langone Health, says the severity of Australia's flu season is definitely cause for concern. "I would expect that it's probably going to be another bad flu year [in the US] based on that data," she tells Health.

Dr. Raabe explains many studies that have mapped out flu seasons over time have shown that the severity of the flu season in Australia correlates with that in the US. "It seems to be relatively accurate in the number of cases," she says, "but sometimes there are some differences in the strains that go around."

The flu vaccine is also slightly different in each hemisphere, she says. The vaccine that's administered around the US is created based on what strains are circulating in both Australia and the US (because some strains from Australia migrate to the Northern Hemisphere). That means there is a chance the US could have a more effective vaccine than what Australia had this year, making for a less severe season; though, again, it could still be bad by US standards. 

To prepare, Dr. Raabe suggests getting the flu shot early, at least by the end of October. The US flu season typically peaks between December and February, but the vaccine takes about two weeks to be effective, and you'll want to be prepared in case the season peaks early like it did in Australia. "There have been years when we've peaked as early as October," Dr. Raabe says. 

The vaccine may not totally eliminate the possibility that you'll get the flu, but it's the best way to protect yourself, and even if you do get sick, you'll lower your chances of developing more serious flu-related issues, like pneumonia.

The CDC estimates that between 12,000 and 79,000 people die from the flu each year, and getting the vaccine is the most effective way to get that number down. 

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